Insulin receptor substrate 1 binds two novel splice variants of the regulatory subunit of phosphatidylinositol 3-kinase in muscle and brain.
Insulin receptor substrate 1 binds two novel splice variants of the regulatory subunit of phosphatidylinositol 3-kinase in muscle and brain.
复制标题
胰岛素受体底物 1 结合肌肉和大脑中磷脂酰肌醇 3-激酶调节亚基的两个新剪接变体。
DOI：
10.1128/mcb.16.5.2195
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发表时间：
1996
影响因子：
5.3
通讯作者：
Kahn,CR
中科院分区：
文献类型：
--
作者：
Antonetti,DA;Algenstaedt,P;Kahn,CR
我们已经确定了两个新的选择性剪接形式的磷脂酰肌醇（PI）3-激酶的p85 a调节亚基的表达筛选的人骨骼肌库与磷酸化杆状病毒产生的人胰岛素受体底物1。一种形式在编码Src同源2（SH 2）结构域和SH 2结构域间/p110结合区的整个区域与p85 a相同，但在核苷酸953的5′侧与p85 a序列不同，其中整个断裂点簇基因和SH 3区域被独特的34个氨基酸N末端取代。这种形式的估计分子量约为53 kDa，被称为p85/AS 53。第二种形式与p85和p85/AS 53相同，除了在SH 2结构域之间插入24个核苷酸，导致天冬氨酸605被9个氨基酸取代，在已知的丝氨酸自磷酸化位点（Ser-608）附近增加了两个潜在的丝氨酸磷酸化位点。北方（RNA）分析揭示p85 a的广泛组织分布，而p85/AS 53在骨骼肌和脑中占优势，并且插入异构体限于心肌和骨骼肌。使用抗p85多克隆抗体和特异性抗p85/AS 53抗体的Western印迹（免疫印迹）分析证实了p85/AS 53蛋白的组织分布，并表明骨骼肌中p85/AS 53蛋白的表达比p85高约7倍。在共沉淀实验中，p85和p85/AS 53都与p110结合，但在胰岛素刺激后，p85 a本身似乎优先与胰岛素受体底物1结合。这些数据表明PI 3-激酶的p85 a调节亚基的基因可以进行组织特异性选择性剪接。PI 3-激酶调节亚基的两种新的剪接变体存在于骨骼肌、心肌和脑中;这些变体在活性上可能具有重要的功能差异，并且可能在组织特异性信号中发挥作用，例如胰岛素刺激的葡萄糖转运或神经递质分泌或作用的控制。
We have identified two novel alternatively spliced forms of the p85a regulatory subunit of phosphatidylinositol (PI) 3-kinase by expression screening of a human skeletal muscle library with phosphorylated baculovirus-produced human insulin receptor substrate 1. One form is identical to p85a throughout the region which encodes both Src homology 2 (SH2) domains and the inter-SH2 domain/p110 binding region but diverges in sequence from p85a on the 5′ side of nucleotide 953, where the entire break point cluster gene and SH3 regions are replaced by a unique 34-amino-acid N terminus. This form has an estimated molecular mass of ~53 kDa and has been termed p85/AS53. The second form is identical to p85 and p85/AS53 except for a 24-nucleotide insert between the SH2 domains that results in a replacement of aspartic acid 605 with nine amino acids, adding two potential serine phosphorylation sites in the vicinity of the known serine autophosphorylation site (Ser-608). Northern (RNA) analyses reveal a wide tissue distribution of p85a, whereas p85/AS53 is dominant in skeletal muscle and brain, and the insert isoforms are restricted to cardiac muscle and skeletal muscle. Western blot (immunoblot) analyses using an anti-p85 polyclonal antibody and a specific anti-p85/AS53 antibody confirmed the tissue distribution of p85/AS53 protein and indicate a ~7-fold higher expression of p85/AS53 protein than of p85 in skeletal muscle. Both p85 and p85/AS53 bind to p110 in coprecipitation experiments, but p85a itself appears to have preferential binding to insulin receptor substrate 1 following insulin stimulation. These data indicate that the gene for the p85a regulatory subunit of PI 3-kinase can undergo tissue-specific alternative splicing. Two novel splice variants of the regulatory subunit of PI 3-kinase are present in skeletal muscle, cardiac muscle, and brain; these variants may have important functional differences in activity and may play a role in tissue-specific signals such as insulin-stimulated glucose transport or control of neurotransmitter secretion or action.